Significance Despite the fact that STDs including HIV cause sever morbidity and mortality in women, there has never been a successful vaccine against one of these pathogens. This may be due to the fact that very little is known about the immune system in the female genital tract. It is clear from studies in rodents that the ovarian hormone cycle can affect the expression of immunity in the female genital tract. This is information may enhance the ability to generate protective immune responses in the genital tract through vaccination. Objective This study was designed to determine if the menstrual cycle of primates affects local genital tract immune responses . Results Twelve rhesus macaques were immunized IM with tetanus toxoid (TT) and orally with cholera toxin (CT). The pattern of antibody responses in serum, vaginal secretions and rectal secretions were analyzed. There were no significant or consistent pattern of antibody levels that seemed to be related to the menstrual cycle. However, the highest antibody levels were seen around menstruation, and this is probably due to contamination of secretions with menstrual blood. In addition T cell proliferative responses were assessed at different stages of the menstrual cycle. In contrast, T cell proliferative responses were markedly reduced in animals during the luteal phase of the menstrual cycle. Thus, it seems that the T cell portion of the immune system is affected by the monthly pattern of hormone secretion. Future Directions We are continuing to analyze B cell activity and all immune cell populations in the female reproductive tracts of the animals in this study. We will eventually determine if the timing of immunization with regard to the menstrual cycle affects immune responses. KEYWORDS hormonal regulation of immunity, female genital tract